Role of the instrument transmission factor in the epidemiology of viral hepatitis. II. Methods, materials, chief results]

The authors conducted a prospective controlled epidemiological observation in two towns of the Moldavian SSR. There were 50 000 persons under observation. Over 300 000 parenteral manipulations carried out in them were recorded. Analysis of the materials obtained on the Minsk-22 computer demonstrated the same incidence of viral hepatitis in the groups given parenteral manipulations and without them. Consequently, the instrumental transmission factor had no essential significance in the epidemiology of viral hepatitis, this corresponding to the results of the authors' preceding theoretical study.     

Experimental study, using a pulmonary model, of the pathogenic properties of genetically related strains of Sh. flexneri, differing in their ability to cause keratoconjunctivitis]

Complex microbiological and morphological study of the genetically connected Sh. flexneri strains, avirulent by keratoconjunctival test showed that the greatest extent of the virulent loss was revealed in shigellae with mutation in the area glpK-gene: they lost the capacity to penetrate into the cells of the bronchial epithelium, to resist local leukocytic reaction and to produce an injurious action on the pulmonary vessels. Shigellae with the replaced kcpA- gene area mostly lost the capacity to penetrate into the epithelial cells of mouse bronchi and were eliminated from the epithelium by the 9th hour after the administration. Xyl--avir-hybrids obtained from crossing of Sh flexneri with the streptomycin-resistant E. coli K12 donors were characterized by the loss of the capacity to prolonged reproduction in the organism of mice with the retention of the capacity to penetration into the epithelium, of the influence on the development of the leukocytic reaction and of the damaging effect on the pulmonary capillaries.     

Genetic characteristics and trends in the spread of a new Shigella flexneri subserovar with the antigenic formula IV:7,8

As the result of experiments with the conjugation of S. flexneri strains 4 belonging to an unusual subserovar (IV: 7,8) with Escherichia coli donor strains K12 Hfr C and Hfr H, as well as experiments with converting phages IV and 7,8, this new subserovar of S. flexneri 4, similarly to other S. flexneri subserovars, was proved to be the Y-variant of shigellae rendered lysogenic by the two above phages. The experiments also revealed that 97.9% of all S. flexneri strains 4 (IV: 7,8) under study possessed invasive properties and were capable of inducing specific keratoconjunctivitis in guinea pigs. Observations on the isolation of S. flexneri strains 4 belonging to the new serovar (IV: 7,8), carried out by the All-Union Shigelloses Center on its basal territories in 1980-1984, made it possible to establish the tendency towards a wider circulation of this infective agent in the USSR.     

The adhesive properties of a nonenteropathogenic strain of Escherichia coli in systems in vitro on isolated rat enterocytes and in vivo

The adhesive properties and colonizing capacity of E. coli strain O83, isolated from feces of healthy humans and marked according to its resistance to rifampicin and nalidixic acid, were studied. In vivo experiments on germ-free rats revealed that these bacteria were capable of colonizing intestinal mucosa; colonization increased from the small to large intestine and E. coli cells were mainly concentrated in the intestinal lumen and in mucin. In vitro studies showed that this nonenteropathogenic E. coli strain possessed pronounced adhesive properties with respect to the colonic cells of germ-free rats; these properties were considerably less pronounced with respect to the enteric cells of the small intestine. The electron microscopic study of E. coli cells revealed the presence of fimbriae and fibrillae on their surface.     

Ability of Citrobacter freundii strains isolated in acute intestinal infections to produce LT-enterotoxin

C. freundii enteropathogenic strains were found to be capable of producing choleroform thermolabile enterotoxin. Thus, in the study of 96 C. freundii strains 38 enterotoxin-producing cultures (39.5%) were revealed by means of the molecular-biological techniques and 29 such cultures (30.0%), by means of the radioimmunoassay (RIA). 100% coincidence was noted in the results of tests for enterotoxigenicity, made by means of RIA or hybridization techniques with the use of the LT-probe containing a cloned fragment with the gene coding the synthesis of LT-enterotoxin in enterotoxigenic Escherichia coli. At the same time only 29 out of 38 Citrobacter strains found to be positive in the hybridization tests, yielded the positive result when tested in RIA for the presence of LT-enterotoxin. This fact should be taken into consideration in the determination of enterotoxin-producing cultures isolated in acute enteric infections, as the method of genetic probing is capable of bringing out the genetic information in bacteria even in the absence of its phenotypical expression.     

Membrane Lipids and Osmolytes Composition of Xerohalophilic Fungus Aspergillus penicillioides during Growth on High NaCl and Glycerol Media

Microbiology - Aspergillus penicillioides may be both xerophilic and halophilic. To study whether there is a difference in the mechanisms of adaptation to low water activity and high NaCl...     

Association of polymophisms of renin-angiotensin and hemostasis system genes with ischemic stroke in Russians from central Russia

The allele and genotype frequencies of 14 SNPs of renin-angiotensin (REN, AGT, AGTR1, AGTR2, BKR2, and ADRB2) and hemostasis (FGB, F2, F5, F7, ITGB3, SERPINE1, MTHFR) system genes, as well as of the ACE insertion-deletion polymorphism, were analyzed in patients with ischemic stroke and in healthy controls matched by age, sex, and ethnicity. Genotyping was performed through the amplification of the selected gene sequences and subsequent hybridization of the labeled fragments with SNP-specific DNA probes on the biochip. There were no significant differences in the allele frequencies of individual genes between the groups of stroke patients and healthy donors. The contribution of the renin-angiotensin and hemostasis system genes to the genetic susceptibility to ischemic stroke in Russians from central Russia was also assessed using the MDR (Multifactor Dimensionality Reduction) approach. The genotype combination FGB G/- x ACE I/- x MTHFR C/- x SERPINE1 5G/5G, the frequency of which was significantly higher in patients with stroke than in healthy controls, was associated with an increased risk of ischemic stroke (P = 0.03, OR = 2.4, 95%CI 1.1?C5.3).